Converging Lenses | GCSE Physics | Doodle Science

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GCSE Science

Script:
A lens is a piece of transparent material, like glass, that uses refraction to form an image by changing the direction of light.
There are two types of lens; converging and diverging.
Converging lenses are shown using this symbol. The lenses curve out on both sides. A ray diagram can be drawn to show the refraction of light through the lens. Light rays that travel through them produce a real image as they all meet at the same point, called the principle focus. The distance between the centre of the lens and this point is called the focal length.
Ray diagrams can be drawn to show how a certain lens will form an image. They follow a set of tedious steps so bear with me. Firstly, a principle axis is drawn through the middle of the lens and the object is placed with its base touching the line, usually represented as an arrow. You then draw two rays from the tip of the object. One passing parallel to the principle axis and then through the principle focus. The other is a straight line through the centre of the lens. The point where the rays meet is the tip of the object’s image. Ray diagrams allow us to work out whether the image will be magnified or diminished, upright or inverted and real or virtual.
The image you see through a magnifying glass is magnified (funnily enough), upright and virtual, because it’s on the same side as the object. This happens to converging lenses when the object is placed between the lens and the principle focus.
You can work out the factor of magnifications by dividing the image height by the object height. For example, the image here appears to be 75cm high when viewed through the magnifying glass but the object is only 25cm. This means the magnification is 3 times bigger than the original object.

[bansrishah]

Thank you so much! I really needed to understand this concept!

[ArranSidhu]

I love your videos! And i would like to offer some constructave criticism, your camera quality is amazing but if you wanted to improve your videos I would recomend upgradeing your mic. Keep up the good work!

[experiencebg]

Your videos are really helpful and well made. They should be more popular!

[lavsri]

Please note that it is 'principal focus' and not 'principle focus'. When we say 'principle of moments', we use the one with 'le'

[ShunGoukuSatsu]

This was really helpful, as the way magnification works was quite ambiguous to me.

[kitkit]

This video is helpful but it is really fast!

[BigStuffedRhino]

Great video but you kind of skipped over what the difference between a real and a virtual image is?